Enumerate network interfaces

Author: tstenner

CMakeLists.txt

@@ -54,6 +54,8 @@ add_library(lslobj OBJECT
 	src/lsl_outlet_c.cpp
 	src/lsl_streaminfo_c.cpp
 	src/lsl_xml_element_c.cpp
+	src/netinterfaces.h
+	src/netinterfaces.cpp
 	src/portable_archive/portable_archive_exception.hpp
 	src/portable_archive/portable_archive_includes.hpp
 	src/portable_archive/portable_iarchive.hpp
@@ -145,6 +147,7 @@ target_link_libraries(lslboost
 		Threads::Threads
 	PRIVATE
 		$<$<PLATFORM_ID:Windows>:bcrypt>
+		$<$<PLATFORM_ID:Windows>:iphlpapi>
 	)
 target_compile_features(lslboost PUBLIC cxx_std_11 cxx_lambda_init_captures)
 

src/netinterfaces.cpp

@@ -0,0 +1,125 @@
+#include "netinterfaces.h"
+#include "loguru/loguru.hpp"
+
+using lslboost::asio::ip::address_v4;
+
+lslboost::asio::ip::address_v6 sinaddr_to_asio(sockaddr_in6 *addr) {
+	lslboost::asio::ip::address_v6::bytes_type buf;
+	memcpy(buf.data(), addr->sin6_addr.s6_addr, sizeof(addr->sin6_addr));
+	return lslboost::asio::ip::make_address_v6(buf, addr->sin6_scope_id);
+}
+
+#if defined(_WIN32)
+#undef UNICODE
+#include <winsock2.h>
+// Headers that need to be included after winsock2.h:
+#include <iphlpapi.h>
+#include <ws2ipdef.h>
+
+typedef IP_ADAPTER_UNICAST_ADDRESS_LH Addr;
+typedef IP_ADAPTER_ADDRESSES *AddrList;
+
+std::vector<lsl::netif> lsl::get_local_interfaces() {
+	// It's a windows machine, we assume it has 512KB free memory
+	DWORD outBufLen = 1 << 19;
+	AddrList ifaddrs = (AddrList) new char[outBufLen];
+
+	std::vector<lsl::netif> ret;
+
+	ULONG res = GetAdaptersAddresses(AF_UNSPEC,
+		GAA_FLAG_INCLUDE_PREFIX | GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_DNS_SERVER, NULL, ifaddrs,
+		&outBufLen);
+
+	if (res == NO_ERROR) {
+		for (AddrList addr = ifaddrs; addr != 0; addr = addr->Next) {
+			// Interface isn't up or doesn't support multicast? Skip it.
+			LOG_F(INFO, "netif '%s' (status: %d, multicast: %d", addr->AdapterName,
+				addr->OperStatus, !addr->NoMulticast);
+			if (addr->OperStatus != IfOperStatusUp) continue;
+			if (addr->NoMulticast) continue;
+
+			lsl::netif if_;
+			if_.name = addr->AdapterName;
+			if_.ifindex = addr->IfIndex;
+
+			// Find the first IPv4 address
+			if (addr->Ipv4Enabled) {
+				for (Addr *uaddr = addr->FirstUnicastAddress; uaddr != 0; uaddr = uaddr->Next) {
+					if (uaddr->Address.lpSockaddr->sa_family != AF_INET) continue;
+
+					if_.addr = lslboost::asio::ip::make_address_v4(
+						ntohl(reinterpret_cast<sockaddr_in *>(uaddr->Address.lpSockaddr)
+								  ->sin_addr.s_addr));
+					ret.emplace_back(std::move(if_));
+					break;
+				}
+			}
+
+			if (addr->Ipv6Enabled) {
+				LOG_F(INFO, "\tIPv6 ifindex %d", if_.ifindex);
+				for (Addr *uaddr = addr->FirstUnicastAddress; uaddr != 0; uaddr = uaddr->Next) {
+					if (uaddr->Address.lpSockaddr->sa_family != AF_INET6) continue;
+
+					if_.addr = sinaddr_to_asio(
+						reinterpret_cast<sockaddr_in6 *>(uaddr->Address.lpSockaddr));
+					ret.emplace_back(std::move(if_));
+					break;
+				}
+			}
+		}
+	} else {
+		LOG_F(ERROR, "Couldn't enumerate network interfaces: %d", res);
+	}
+	delete[]((char *)ifaddrs);
+	return ret;
+}
+#elif defined(__APPLE__) || defined(__linux__)
+#include <arpa/inet.h>
+#include <ifaddrs.h>
+#include <map>
+#include <net/if.h>
+#include <sys/types.h>
+
+std::vector<lsl::netif> lsl::get_local_interfaces() {
+	std::vector<lsl::netif> res;
+	ifaddrs *ifs;
+	if (getifaddrs(&ifs)) {
+		LOG_F(ERROR, "Couldn't enumerate network interfaces: %d", errno);
+		return res;
+	}
+	for (auto addr = ifs; addr != nullptr; addr = addr->ifa_next) {
+		// No address? Skip.
+		if (addr->ifa_addr == nullptr) continue;
+		LOG_F(INFO, "netif '%s' (status: %d, multicast: %d, broadcast: %d)", addr->ifa_name,
+			addr->ifa_flags & IFF_MULTICAST, addr->ifa_flags & IFF_UP,
+			addr->ifa_flags & IFF_BROADCAST);
+		// Interface doesn't support multicast? Skip.
+		if (!(addr->ifa_flags & IFF_MULTICAST)) continue;
+		// Interface isn't active? Skip.
+		if (!(addr->ifa_flags & IFF_UP)) continue;
+
+		lsl::netif if_;
+
+		if (addr->ifa_addr->sa_family == AF_INET) {
+			if_.addr = lslboost::asio::ip::make_address_v4(
+				ntohl(reinterpret_cast<sockaddr_in *>(addr->ifa_addr)->sin_addr.s_addr));
+			LOG_F(INFO, "\tIPv4 addr: %x", if_.addr.to_v4().to_uint());
+		} else if (addr->ifa_addr->sa_family == AF_INET6) {
+			if_.addr = sinaddr_to_asio(reinterpret_cast<sockaddr_in6 *>(addr->ifa_addr));
+			LOG_F(INFO, "\tIPv6 addr: %s", if_.addr.to_string().c_str());
+		} else
+			continue;
+
+		if_.ifindex = if_nametoindex(addr->ifa_name);
+		res.emplace_back(std::move(if_));
+	}
+	freeifaddrs(ifs);
+	return res;
+}
+#else
+
+std::vector<lsl::netif> get_interface_addresses() {
+	LOG_F(WARN, "No implementation to enumerate network interfaces found.");
+	return std::vector<lsl::netif>();
+}
+#endif

src/netinterfaces.h

@@ -0,0 +1,19 @@
+#pragma once
+#include "common.h"
+#include <cstdint>
+#include <string>
+#include <vector>
+#include <boost/asio/ip/address.hpp>
+
+namespace lsl {
+
+class netif {
+public:
+	lslboost::asio::ip::address addr;
+	uint32_t ifindex;
+	std::string name;
+};
+
+/// Enumerate all local interface addresses (IPv6 index, IPv4 address)-pairs
+std::vector<netif> get_local_interfaces();
+} // namespace lsl